Abstract: A closure lock which utilizes the operating motor for moving of the closure as the locking mechanism. A shorting circuit is applied across the motor when the closure is in an at-rest position. Any attempt at manually moving of the closure between the closed position of the closure and the open position of the closure will require the rotor of the motor to be rotated relative to the stator of the motor. This requires a significant amount of motor drag to be overcome which is difficult and thereby functions as a locking mechanism preventing operating of the closure. This closure lock can be bypassed by an authorized person by the opening of a manually operated switch which will permit the closure to be easily moved between its open and closed position.

Abstract: Operators for sliding gates including a solenoid-operated detent for engaging a gear of the gate drive motor shaft speed reducer and locking the associated gate, and a key-operated cam for disengaging the detent from the gear.

Abstract: An electronic safety device circuit is disclosed. This circuit includes two integrated circuit operational amplifiers, the first connected as an operational amplifier and the second connected as a follower. The output pin of the first amplifier is connected to the positive input pin of the second amplifier through a diode. The positive input pin of the second amplifier is connected to a memory capacitor. The output pin of the second amplifier is connected to the negative input pin of the first amplifier. A switching network is provided for grounding the positive input pin of the first amplifier and discharging the memory capacitor.